Pitaya Bloom and Pitaya Fruit Production: For the pitaya cactus to bloom and fruit most abundantly, it is best to not water the pitaya cactus plant or water it very little in the time time before the pitaya cactus will bloom. Then, once the pitaya cactus has bloomed and is beginning to produce fruit, the water requirements will increase. Irrigate the pitaya cactus to give it sufficient water to produce the water rich fruit, then when the fruiting season has ended, watering can again be reduced or eliminated.